Hydraulic accumulators



Oct. 2, 1956 J. H. STANBURY 2,764,999

HYDRAULIC ACCUMULATORS Filed Aug. 29, 1952 2 Sheets-Sheet l INVENT R B3 WM r ATTORNEYS HYDRAULIC ACCUMULATORS Patent John Herbert Stanbury, Gloucester, England, assignor to British Messier Limited, Gloucester, England, a British company This invention comprises improvements in or relating to hydraulic accumulators and the like. i

It is an object of the present invention to provide an apparatus which will not only act as a hydraulic accumulator but will also maintain simultaneously a reduced hydraulic pressure in a pipe-line connected to the accumulator; that is to say more than one pressure is maintained by the device in more than one circuit at the same time. Such an apparatus saves the necessity of using two difierent accumulators or their equivalent in certain hydraulic circuits. For example, it is essential on certain aerial Weapons to use, for the hydraulic system, a hydraulic reservoir which is maintained under pressure so that the Weapon can operate at high altitude. It is also essential to use an accumulator in the system to augment the output of the pump. Normally these two requirements would mean that two air volumes would have to he inflated in order to achieve the necessary pressurisation. The present invention relates to a means of achieving this result with a single air-chamber.

According to the present invention a hydraulic accumulator of the type which contains a sliding separator piston between a high pressure chamber and the high pressure hydraulic fluid chamber is employed, having an extension to constitute a low pressure chamber separated from the high pressure accumulator fluid chamber by a diaphragm or other separating wall, the low pressure chamber containing a sliding piston to bear upon the low pressure liquid therein and the sliding piston being connected to a ram or its equivalent of smaller area than the piston which enters the hydraulic pressure accumulator chamber.

By this means liquid in the low pressure chamber is maintained under a pressure relative to that of liquid in the high pressure chamber which depends on the ratio of the area of the sliding piston in the low pressure chamber and of the ram connected to it which enter the high pressure chamber.

One construction in accordance with the invention will now be described by way of example, reference being made to the accompanying drawings in which;

Figure 1 is a diagrammatic representation of the parts, and

Figure 2 is a longitudinal section through an accumulator.

In Figure 1 the pump 11 is connected to a delivery pipe 12 and draws from suction pipe 13. An accumulator 14 is connected at one end by a branch 15 to the delivery pipe 12 and at the other end by a branch 16 to the suction pipe 13. The accumulator is sub-divided by a diaphragm 17 and above the diaphragm is an air space 18 which can be inflated through fitting 19. A sliding separator piston 20 separates hydraulic liquid in the chamber 21 from the air chamber 18. A sliding piston 22 in the lower end of the accumulator carries a ram 23 which passes through the diaphragm 17. The space above the piston 22 is connected to atmosphere through vent 24.

The pressure in the chamber 21 is equal to the air pressure in chamber 18. The pressure in the chamber 25 below the piston 22 is less than the pressure in the air chamber 18 in the ratio of the area of the ram 23 to the area of the piston 22.

If" the accumulator just described is used in a guided missile or high-altitude aircraft, the pump 11 may generate hydraulic pressure at, say, three thousand pounds per square inch and the chamber 18 will be correspondingly inflated. The delivery pipe 12 is connected to devices which are to be operated on the missile or aircraft. The suction tank connected to pipe 13 is kept under a moderate pressure by piston 22 irrespective of the atmospheric pressure at 24.

Referring to Figure 2 filed herewith, this shows a particular construction of accumulator, still in accordance with the diagrammatic figure just described. An outer spherical shell 30 formed in two halves welded along line 31 has welded in it on opposite sides two co-axial retaining rings 32 33. In the ring 32 is fitted a high-pressure accumulator cylinder 34 (corresponding to cylinder 14 already described). This is held in place by a flange 35 hearing against the interior of ring 32 and is sealed by a rubber gland-ring 36. At its inner end it has a flange 37 which fits the ring 33 and is sealed by a gland-ring 3,8. The outer end of the cylinder 34 is closed by a cover (not shown) screw 6d into screw-threads 39.

In the cylinder 34 is a separator piston 40 (corresponding to piston 29 previously described). An inflator connection 41 (corresponding to 19) is provided in the shell 30 and the air has access to the interior of cylinder 34 through ports 42 in its Wall.

The inner end of cylinder 34 is closed in by a conical diaphragm 44 (corresponding to 17) and through the diaphragm passes a ram 43 (corresponding to 23). The ram is further guided by a spider 45 secured inside the diaphragm 44 and pierced by air-holes 46. On the ram is a piston 52 (corresponding to 22) which works in a cylinder 48 screwed into the retaining ring 33 and fitting against the back of flange 37. This cylinder is closed by acover 49 having a nipple 50 for attachment of a pipe connection corresponding to the connection 16. The space behind the piston 52 is connected to atmosphere by ports 54 (corresponding to 24) and an annular space between cylinder 48 and ring 33. The cylinder 48 is buttressed against the ring 33 by lugs 51 which project from it at intervals all around.

It will he observed that in this construction all the parts of the previous figure are reproduced, but by enclosing them in the spherical shell 30 the stresses on the cylinder wall 34 are reduced (and so the thickness and weight is less) while the air-space is increased, and the sphe ica she l 0 is o t e b 'sh fo es n rna pressure.

I claim:

1. A hydraulic accumulator comprising in combination a low pressure cylinder, a high pressure cylinder in line axially therewith, a diaphragm separating the tWo cylinders, a piston in the high pressure cylinder, a piston in the low pressure cylinder, a ram connected with the latter piston which ram is of smaller diameter than said piston and extends through the diaphragm into the high pressure cylinder, a hydraulic fluid pressure connection to one end of said high pressure cylinder, a hydraulic fluid connection to the low pressure cylinder on the other side of the piston therein from the ram, a substantially spherical outer vessel enclosing and providing an enclosed space around the high pressure cylinder, with connecting passages between the space in said vessel around the cylinder and the end of the cylinder opposite that having the hydraulic fluid pressure con- 6 nection, and an inflation connection in the wall of the spherical vessel.

2. An accumulator as claimed in claim 1 wherein a port is provided in the wall of the low pressure cylinder between the piston therein and the diaphragm, which port is open to atmosphere.

3. An accumulator as claimed in claim 1, wherein the end of the high pressure cylinder that communicates with the space in the spherical outer vessel is nearer the diaphragm, and the hydraulic connection thereto is to the end further from the diaphragm, said piston disposed in the high pressure cylinder serving to separate hydraulic fluid entering through the hydraulic fluid connection and air entering at the opposite end of the cylinder.

4. A hydraulic accumulator comprising a substantially spherical outer vessel, low and high pressure cylinders extending within said vessel from opposite sides thereof to meet one another, a diaphragm which separates the low pressure cylinder from the high pressure cylinder, sliding pistons in said cylinders, a ram connected with the piston of the low pressure cylinder which ram is of smaller diameter than the piston to which it is connected and extends slidably through the diaphragm in a fluid-tight manner into the high pressure cylinder, high and low pressure fluid connections to the outer ends of the high and low pressure cylinders respectively, an inflation connection in the shell of the spherical vessel, and passages connecting the space in the high pressure cylinder between the piston therein and the diaphragm with the space in the spherical vessel surrounding the cylinders.

5. A hydraulic accumulator comprising a substantially spherical outer vessel, low and high pressure cylinders having their axes in alignment and extending within said vessel from opposite sides thereof to meet one another, a diaphragm separating the low pressure cylinder from the high pressure cylinder which diaphragm is frusto-conical in form withits smaller diameter end directed into the low pressure cylinder, sliding pistons in said cylinders, a ram connected with the piston of the low pressure cylinder which ram is of smaller diameter than the piston to which it is connected and extends slidably through the diaphragm in a fluid-tight manner into the high pressure cylinder, high and low pressure fluid connections to the outer ends of the high and low pressure cylinders respectively, an inflation connection in the shell of the spherical vessel, and passages connecting the space in the high pressure cylinder between the piston therein and the diaphragm with the space in the'spherical vessel surrounding the cylinders.

6. An accumulator as claimed in claim 5, wherein the pistons are substantially hemispherical in form, bulging toward the outer ends of the cylinders.

7. An accumulator as claimed in claim 5, wherein a spider is carried by the diaphragm on the high pressure side thereof to afford an additional guide for the ram during its sliding.

8. A hydraulic accumulator comprising a substantially spherical outer vessel, low and high pressure cylinders having their axes in alignment and extending within said vessel from opposite sides thereof to meet one another, the low pressure cylinder being of greater diameter than the high pressure cylinder, a diaphragm separating the low pressure cylinder from the high pressure cylinder which diaphragm is frusto-conical in form with its smaller diameter end directed into the low pressure cylinder, sliding pistons in said cylinders which pistons are each of substantially hemispherical form bulging toward the outer ends of the cylinders, a ram on the piston of the low pressure cylinder which ram is of smaller diameter than the piston which carries it and extends slidably through the diaphragm in a fluid-tight manner into the high pressure cylinder, a spider carried within the diaphragm cone on the high pressure side thereof and through which the ram passes so that the spider affords an additional guide for the ram during its sliding, high and low pressure hydraulic fluid connections to the outer ends of the high and low pressure cylinders respectively, an air inflation connection in the shell of the spherical vessel, and air passages connecting the space in the high pressure cylinder between the piston therein and the diaphragm with the space in the spherical vessel surrounding the cylinders.

9. An accumulator as claimed in claim 8, wherein passages are provided connecting the cylinder space between the diaphragm and the low pressure cylinder with atmosphere.

10. An accumulator as claimed in claim 4, wherein the low pressure cylinder extends through an opening at one side of the substantially spherical outer vessel, a support tube surrounding the low pressure cylinder has one end united to the shell of the outer vessel around said opening and extends inwardly therefrom into said vessel, the tube is internally screw threaded and the inner end of the low pressure cylinder is externally threaded and screwed into said tube, the external diameter of the low pressure cylinder outwardly of the screw threaded connection is smaller than the internal diameter of the tube so that an annular passage is provided between the tube and the cylinder, and ports in the wall of the low pressure cylinder at the inner end thereof serve to connect the space within said cylinder between its piston and the diaphragm to atmosphere by way of said annular passage.

References Cited in the file of this patent UNITED STATES PATENTS 2,397,270 Kelly Mar. 26, 1946 2,673,527 Ashton et al Mar. 30, 1954 FOREIGN PATENTS 581,268 Great Britain Oct. 7, 1946 5 9.933 Great Britain Mar. 24, 1948 

